This is what a buyer checks before they shortlist a automotive, rail, marine and aerospace supplier.
What does a Tier 1 or OEM buyer check before sourcing a new part from you?
They check your IATF 16949 status with the certificate number, the PPAP level you can submit, and whether you have process capability evidence. Automotive sourcing is a documented process, and a supplier who cannot show the documents cannot enter it whatever the part costs.
A sourcing engineer is assembling a bidder list that has to survive a supplier quality review.
Reviewed 4 August 2026 · Written for automotive component manufacturers selling to business buyers
What does a Tier 1 or OEM buyer check before sourcing a new part from you?
What a buyer needs to identify the product
These are the fields a buyer scans before deciding whether you are worth contacting. Missing one of them usually ends the visit without an email.
- 1
Part families and processes
The buyer matches their commodity to your process route.
- 2
Materials and grades
Determines feasibility and validation route.
- 3
Annual capacity per part family
Programme volumes are fixed; your capacity has to meet them.
- 4
Tolerance and process capability
Cpk expectations are explicit in automotive.
- 5
Tooling capability and ownership
Decides timeline and investment structure.
- 6
Customer segments already supplied
Tier 1, OEM and aftermarket are different qualification regimes.
- 7
Plant locations
Proximity and dual-sourcing are real sourcing criteria.
The documents buyers ask for
Not all of them belong on a public page. Naming the ones you can issue is what separates a supplier who can be audited from one who cannot.
| Document | What it proves | Where it belongs |
|---|---|---|
| IATF 16949 certificateAsked at: the first gate — usually before any technical review | The automotive quality system, with certificate number and certification body | Publish it |
| PPAP submission capability with levelAsked at: sourcing decision | That you can produce the production part approval package the customer requires | Publish it |
| Part Submission WarrantAsked at: part approval | Formal declaration that parts meet requirements | Per shipment |
| Control plan and APQP evidenceAsked at: supplier quality assessment | That quality is planned into the process, not inspected in | Name it, share on request |
| SPC and Cpk dataAsked at: technical review | Demonstrated process capability on the characteristics that matter | Name it, share on request |
| IMDS submission capabilityAsked at: onboarding | Material data reporting into the automotive industry system | Publish it |
| Run-at-rate or capacity studyAsked at: before programme award | That the quoted volume is achievable at the quoted quality | Name it, share on request |
Where auto components sites lose the enquiry
Each of these is common, cheap to fix, and costs an enquiry that never arrives — so nobody ever reports it.
IATF certification claimed without a certificate number
Automotive buyers verify against the IATF database. An unverifiable claim is worse than none, because it will be checked.
No PPAP level stated
The buyer cannot tell whether onboarding is routine or a development project, so they assume the expensive answer.
No process capability evidence anywhere
Supplier quality engineers screen on capability. Its absence removes you at the stage before anyone reads your price.
What the enquiry form should ask
A form that collects these can be answered properly the first time. A form that collects a name and a message cannot.
Enquiry form — auto components
Enough to reply usefully, short enough that a buyer finishes it.
- Part drawing and customer part number
- Everything downstream depends on it.
- Material and specification
- Determines process route and validation.
- Annual volume and programme life
- The basis of the whole commercial case.
- PPAP level required
- Drives cost and timeline of onboarding.
- Tooling status
- New, transfer or customer-owned changes the project.
- SOP date
- Start of production is the fixed point everything works back from.
Questions suppliers ask
Should the IATF certificate number be published?
Yes, along with the certification body and the site it covers. Automotive buyers verify certification against the public IATF database as a matter of routine, and giving them the number is simply removing a step from a check they will perform anyway.
We supply the aftermarket, not OEMs. Does this still apply?
Partly. Aftermarket buyers care less about PPAP and more about fitment data, cross-references to OE part numbers, packaging and warranty. Publish the cross-reference table — it is the single most valuable page an aftermarket supplier can have.
How do we show capability without naming customers under NDA?
Describe the commodity, the process, the tolerance held, the annual volume and the segment, without the customer name. Sourcing engineers are assessing whether you have done work of that type at that level, and that can be established without breaching an agreement.
Documents and standards named here are the ones buyers in this industry commonly ask for; requirements vary by market, customer and contract, so treat this as a starting checklist rather than a compliance list. Clearer pages can help discovery and evaluation. They do not guarantee rankings, AI citations, enquiries or revenue.
Illustrative
An enquiry from this search looks like: Part drawing and customer part number · Annual volume and programme life · SOP date · Material and specification
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